Today, let's reinvent the wheel. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.

As nearly as we can tell
from archaeological evidence, the wheel was
invented somewhere in present-day Iraq or Iran
around 3500 BC. That in itself is suprising,
because it's so late in human history. The other
odd thing about the wheel is that it stayed within
Europe and Asia as long as it did. Wheels were
hardly seen in the American hemisphere until they
were brought into regular use by European settlers
in the 17th century. There's evidence that
11th-century Mexicans had the concept, but no
evidence of its general use.

Of course, we've lived since birth with a hundred
thousand different forms of the wheel. It's hard
for us to imagine what a difficult concept it
represents. But look at it, if you can, from the
standpoint of someone who's never seen one. You
understand movement in a straight line, and you
understand the idea of turning things around. But
can you make a connection between the two? Can you
conceive of making a vehicle go forward by turning
something around?

We've all played the children's game of patting our
head and rubbing our stomach at the same time. It's
very hard to do, because it's hard to conceptualize
these two very different kinds of motion at the
same time.

The conceptual difficulties of the wheel are
compounded if we move to a variation of the idea --
if we move to the hand crank. The crank is another
very common device that you might think had been
with us since the dawn of history, but it has not.
The hand crank has been in general use for only a
thousand years. The Greeks didn't have it. The
Egyptians didn't have it. The vaunted Romans with
their much-praised technology never arrived at this
seemingly simple device.

The hand crank, of course, takes the problem of
converting back-and-forth motion of our upper arm
into a rotational motion, and it freezes this
transformation into one location. In a sense, it
requires that we solve the problem of patting our
head and rubbing our stomach at the same time.

Most of the important ancient inventions seem to
have been made over and over -- at different times
and in different places. Not so the wheel. It seems
to have originated in one place and diffused to
other peoples and other cultures from there. It was
very likely the product of an isolated act of human
ingenuity.

I'm John Lienhard at the University of Houston,
where we're interested in the way inventive minds
work.